READ the general info-there are several types of passes, vary in how many days to use trains etc.

There are also several, now also online, guideboox on howtodo this daunting enterprise. A guy named RickSteves was famous for that for those from US -and CA.

As such the pass IS the ticket for at least 95% of trains that run here in EUR, spread over 33 countries on at last a 100 different companies. You only need to activate traveldays and add the trains used into the app, then a daily QR code will come out and that you show when there is someone checking.

BUT the usual 1st time newbee all seem to want exactly to ride those trains that also need hard to get pesky  REServ. ESpana is the most hard for that, followed by FR-but this only concerns the hi-speed TGV. You can do that via app but also via other means. RES as such is not linked to this trip manual, its separate.

Athinai in GR is way out, look at a decent map and has no connections by train all the way to West-EUR anymore. Those dedicated to no-fly use a ferry from ITaly to get there.

In general you from USA tend also to be waaaaaaaaaaaaaaaay too early for RES etc-trains are not planes, will not take you by the hand to organise it all for you etc. and mostly only open booking for RES 2 month advance, maybe 3. To get a global idea of how long it takes, change where or not etc simply try out a planner (better use another one as EUrail, f.e. bahn.com) simply use a same dayofweek next week or so-it will roughly be the same.

Hi Eurail is a Travel Pass valid in 33 european countries on rail. This Pass is your train ticket.

Validity is given by train companies, the are more than 33 companies. Some trains need a reservation (between 1 and 40 EURO on most routes). Some trains have only optional reservations and others only hop on.

I can tell you to get to Athens by rail is currently not possible (bot only by busses not included in the pass) but you can take a ship from Italy to Greece.

If you only want point to point tickets, visit the website of the train company of the train.